Selective Comminution Applied to Mineral Processing of Critical Metals

Sammanfattning: The outstanding properties of tungsten and tantalum make them valuable metals and, in some cases, irreplaceable in applications. Due to the vital economic importance and limited supply, growing interest places these metals on the critical metals risk list. Due to increasing global demand for these metals, there is also a need to develop more efficient extraction processes. The size reduction of particles commonly assesses coarse comminution processes. Nevertheless, does not include mineralogy and element content.   The primary hypothesis of this research is that the utilization of selective comminution could enhance the efficiency of critical metal extraction, rendering it a valuable and cost-effective method in comparison to conventional approaches. As critical metals do not uniformly distribute across distinct size fractions during coarse comminution processes, owing to the influence of mineralogical composition and texture on particle breakage. To underscore the significant role of mineralogy in breakage, a novel testing procedure is proposed, which involves the concentration of critical metals following compressive breakage, aiming to augment the resolution of coarse comminution models.   This study is dedicated to formulating an analytical methodology and test protocols aimed at analysing and characterizing selective comminution possibilities during compression breakage. The research progresses across three key phases. The primary phase involves the comprehensive characterization of rock materials, encompassing mechanical, chemical, and mineralogical analyses. The subsequent phase involves modelling, followed by the third phase, which entails the technical and economic evaluation of material in a theoretical plant distribution case study.   Mechanical characterization includes laboratory-based compressive crushing, encompassing interparticle breakage, while chemical and mineralogical characterization is conducted by evaluating size-fractioned samples post-compression breakage, employing techniques such as scanning electron microscopy (SEM) and geochemical analysis. These tests yield valuable insights into breakage behaviour, mineral composition, and elemental concentration, with implications for early material rejection strategies.   Geochemical analysis is carried out using inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). Additionally, the production of particles in nano sizes, pressed powder pellets, followed by analysis via Laser Ablation Inductively Coupled Plasma Mass Spectrometry (PPP LA-ICP-MS), offers a cost-effective and suitable means to measure elemental content, circumventing the laborious and costly steps associated with standard techniques such as fused bead and acid digestion.   The data generated through the developed analytical methodology undergoes rigorous analysis and is fitted into a model, which employs a bimodal Weibull distribution for calibration. This concentration model excels in simulating critical metal concentrations based on compression ratios, and it can forecast rare metal concentrations in relation to particle size distributions following compression crushing.   Following comprehensive study, analysis, and modelling of mineral composition, a tool is devised that combines technical and economic models, enabling the optimization of production by enhancing product quality, cost-efficiency, profitability, and capacity. The results demonstrate that the proposed model facilitates the determination and enhancement of process capacity and profitability. Utilizing the technical and economic model offers the prospect of elevating profitability by reconfiguring mass flows based on the mineral composition of the rock, aligning with plant distribution objectives.   In conclusion, the implementation of the developed analytical method enhances the assessment of coarse mineral liberation characteristics, offering fundamental insights into how various ore materials tend to break post-compressive crushing, concerning mineral and elemental distributions. Armed with this information, it becomes possible to propose, refine, and assess the cost of process adjustments, such as machine parameters, plant design, and early material rejection strategies, tailored to the specific properties of each ore.